Today premature infants weighing less than 1 kg may be stabilized and allowed to develop in neonatal intensive care units (NICUs). Magnetic resonance imaging (MRI) is a powerful technique for diagnostic purposes but is not routinely performed on these infants due to a number of technical and logistical challenges.
When a mother has a high-risk pregnancy, it is possible that the baby could be born prematurely and would require treatment in a neonatal intensive care unit or NICU. Also, unexpected early delivery may require that an infant be treated in an NICU.
One difficulty in utilizing MRI for these premature infants is monitoring the vital signs and life support of the infant during MR examination. Parameters that must be monitored during examination include electrolyte levels, hydration and temperature. A second difficulty in utilizing MRI is that the infant must be moved from an incubator or isolette into and out of the MR scanner. This movement places the infant at risk for injury.
Despite challenges, MRI has the potential to play an important diagnostic role in the care and management of neonates. The full use of this imaging technique requires that the imaging take place as early as the first few hours of life. At this stage, however, the infants are hemodynamically unstable. Accordingly, transporting and maintaining homeostasis in these fragile infants presents difficulty.
Another challenge in using MRI for neonates is that MRI systems are frequently located in Radiology departments outside of and perhaps distant from the NICU. Consequently, the neonate must be escorted out of the NICU. This may present certain logistical and technical challenges with respect to controlling the neonate's environment. Furthermore, removing staff from the NICU to transfer and attend to one baby outside the NICU can place the remaining babies in the NICU at increased risk of a reduced level of care due to decreased staff coverage.
An MR compatible transport incubator and imaging system has been developed (Dumoulin et. al.) and is currently in use. Concepts in Magnetic Resonance (Magnetic Resonance Engineering), Vol. 15(2) 117-128 (2002). This system is a self-contained MR compatible transport incubator which carries the infant from the NICU to an MR scanner located in or near the NICU. With this approach the baby must first be transferred from its “home” incubator or isolette in the NICU into the transport incubator. The transport incubator is then moved to the MR scanner where it is docked with the scanner. A portion of the transport incubator containing the baby is then moved into the center of the MR imaging system magnet where MR imaging is performed. While this approach has the advantage of not disturbing the baby while it is in the transport incubator, even during MR scanning, it has several limitations including: a) infants must be fully detached from the monitoring equipment in their home incubator to be transferred into the transport incubator, b) the MR system that is used for imaging must have a bore large enough to accommodate the portion of the transport incubator containing the baby (thereby requiring a large heavy magnet), c) the baby and its attending staff need to leave the NICU for scanning, and d) because the transport incubator must be fully MR compatible while providing full life support for the baby, the system is heavy and expensive.
An alternate approach to provide MR imaging to newborn babies has been disclosed by Feenan in U.S. Pat. No. 7,599,728. In this approach a relatively smaller MR magnet is employed and MR-compatible incubators are docked to the magnet thereby permitting the baby to be slid into the magnet for imaging. While this approach has the benefit of providing a magnet that is more easily installed in the NICU, it does have several limitations including the need for MR compatible incubators to be used throughout the NICU, or the transfer of a neonate from a non-MR-compatible home incubator to an MR-compatible incubator. This approach also limits the access to the attending staff as they prepare the infant for MR scanning. In particular, the staff must reach through the incubator to push the baby into and out of the magnet.